Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hanh dai » hanh tai, hanh dao, vanh dai
va hanh » van hanh, va thanh, va danh
cua tre » cua te, cuu tre, cua triet
ky dang » ky nang, ky danh
ky tang » ky nang, kho tang, ky trong
va cao » va cac, va co, va dao
tuc va » thuc va, truc va, tuc xa
va cam » va cham, va cac, va cai

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ((ky tang) OR (ky dang)) xa hoi. hieu ((va cam) or (va cao)) tuc va hanh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((ky tang) OR (ky dang)) xa hoi. hieu ((va cam) OR (va cao)) tuc va hanh dai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ((ky tang) OR (ky dang)) xa hoi. hieu ((va cam) or (va cao)) tuc va hanh dai cua tre".
• Adding a wildcard symbol may retrieve word variants: toc sach ((ky tang) OR (ky dang)) xa hoi. hieu ((va cam) or (va cao)) tuc va hanh dai cua tre*.